Continuous, underwater location and orientation tracking is critical for our understanding of submerged objects, especially objects capable of motion. Currently, tags configured to be attached to an aquatic target, such as an animal or boat, allow for only limited location tracking. Investigations of animal habitat use and behavior are important for understanding the ecology of animals and are vital for making informed conservation decisions.
In aquatic environments, it is very difficult to directly observe the behavior of large animals that range widely, such as marine mammals and large pelagic fishes, including sharks, turtles, and dolphins. This is particularly true for feeding behavior because predation events are rarely witnessed. Indeed, much of what is known about the foraging behavior of these animals is derived from a limited number of direct observations in shallow water, from submersible vehicles, and from animal-borne imaging. Given the paucity of such observations, the feeding ecology of large aquatic animals has been inferred from tagging and tracking data, stomach contents, and fatty-acid and stable-isotope analyses. These studies reveal little about actual animal behavior, especially over a period of time and distance.
Similarly, tracking surface or submerged vessels, such as suspected drug traffickers, illegal fishing vessels, enemy submarines, and strategic objects for precise targeting, is of particular importance. For surface vessels, clandestine tracking and monitoring of a target often requires a tag hidden from the crew of the tagged vessel. A tracking tag can be attached below the water line to avoid detection. Currently available tags are not advantageous for submerged tag locations. Satellite tags require an unobstructed link to the satellite, and current underwater acoustic tags have very limited ranges, making a tracking a moving vessel difficult, and potentially detectable by the target.
Furthermore, currently available submergible tags only have transmitting capabilities (e.g. a transmitting pinger for locational information) and no receiving capability. All functions available to the tag, such as tag release, transmission state, or transmission frequency are uncontrollable, and must be preprogrammed.
Historically, electronic tagging data have shown that a variety of large marine predators, including fish, sharks, pinnipeds, whales, marine reptiles, and marine birds, exhibit seasonally recurring migrations in the northeastern Pacific, often between coastal and oceanic habitats. Seasonal migrations often take animals between areas used for foraging and ones used for reproduction. Understanding how a migratory species uses different parts of its range is fundamental to understanding its ecology and life history. There is no way of directly observing and therefore differentiating migratory behaviors such as ‘transiting’, ‘foraging’ and ‘mating’ with current tagging technologies. Instead these behaviors must be inferred from changes in the parameters that are measured (e.g., depth, swim direction, etc.). Further advancements in tagging and subsequent tracking technology are needed for finer scale behavior observation and documentation.
Over the course of the last two decades, new technologies have been developed to track the movements of aquatic targets over multiple spatial and temporal scales. Although these technologies have shown remarkable movements, they do little to reveal what these targets are actually doing. The use of autonomous underwater vehicles (AUVs) has led to the discovery of unique geological, geochemical, and biological phenomena, and to furthering understanding of many important natural processes. Acting as submersible drones, these vehicles can provide data that are virtually impossible to collect with conventional techniques
Currently, the small commercial tags available limit spatial tracking and detection to moored receiver locations or to active pinging and recording from a surface vessel, with no informational receiving capability. This limits the usefulness of these tags. Pop-up archival transmitting (PAT) tags are also available, and because they transmit location though the Argos satellite network, they have large operational ranges. But they too lack information receiving capability, and can only transmit information after it is released from the target.
Successive location transmissions for accurate tracking of position are not reliable as a tagged animal may be too far away from a monitoring buoy, or may not reach the surface often enough to provide satellite communication. Depending on the Argos Location Class, satellite data may only be accurate to >1.5 kilometers radius to >100 meters radius such as currently described at http://www.argos-system.org. Furthermore, tagging systems designed for large oceanic animals are often larger in size and rely on large gauge barbed stainless-steel pins to insert the tag securely into the animal's musculature. While these tags may not be harmful on large species, such tags are impractical and potentially deadly to smaller animals or those without sufficient musculature to maintain the tag. Furthermore, relaying positional information for the purpose of actively tracking with an AUV is impractical. Existing acoustic tags have a range of about 500 m and only transmit, limiting active tracking by a tracking vessel. By communicating through the satellite network, satellite tags have no limit to the distance their positional information can be sent, however both the tagged target and the tracking AUV would need to repeatedly surface to receive the tag's location from the satellite network, making tracking unworkable.
A submergible tag that can receive as well as transmit information would greatly improve the field of underwater tracking. A receiving tag, could be used to send commands or additional information pertaining to the mission the tag was deployed in. A receiving tag, or smart tag, could be commanded to change a number of operational procedures, for example, start or stop the tag's transmissions, or change the transmission frequency. A smart tag can be commanded to release from its target, as opposed to the current time-based release, improving tag recovery or preventing the tag from being discovered. With additional components, such a smart tag could perform a wide range of additional actions upon command, for example engage light, turn on additional sensors, activate an underwater drill, or trigger an explosive device.
Therefore, there is a need for a submersible, smart tag with receiving capabilities. The smart tag, as disclosed herein offers on-demand system modification, including transmitting state and frequency, release, and actuation of additional sensors and equipment.